Deteksi Kavitasi Pada Pompa Sentrifugal Menggunakan Spektrum Getaran dan Spektrum Envelope

Berli P. Kamiel, Deby Arikh Nafsaka, Bambang Riyanta, Azhim Asyratul

Abstract


Abstrak

Kavitasi adalah salah satu indikator penting kondisi operasi sebuah pompa sentrifugal. Fenomena kavitasi ditunjukkan dengan terbentuknya formasi gelembung udara yang kemudian pecah secara tiba-tiba akibat perubahan tekanan pada sisi hisap pompa. Kavitasi dapat menyebabkan kerusakan yang parah komponen pompa terutama bagian sudu atau impeller. Kavitasi biasanya dapat diidentifikasi melalui suara bising dan timbulnya getaran yang berlebihan. Sebuah metode deteksi kavitasi dibutuhkan agar potensi kerusakan lebih lanjut pada pompa sentrifugal dapat diantisipasi secepatnya. Penelitian ini bertujuan menghasilkan sebuah metode deteksi kavitasi menggunakan spektrum getaran dan spektrum envelope pada bentang frekwensi rendah 0-4 kHz dan bentang frekwensi tinggi 4-8,5 kHz. Sinyal getaran pompa direkam menggunakan sebuah akselerometer yang diletakkan pada rumah volute pompa arah aksial. Sinyal getaran kemudian ditransformasikan kedalam spektrum dan spektrum envelope menggunakan  Fast Fourier Transform. Spektrum dan spektrum envelope untuk masing-masing bentang frekwensi dibandingkan antara pompa kondisi normal dan kondisi tiga level kavitasi kavitasi. Hasil penelitian menunjukkan bahwa spektrum frekwensi rendah dapat digunakan untuk mendeteksi kavitasi level 3 yang ditunjukkan dengan peningkatan amplitudo frekwensi poros sebesar 47,6 Hz dan ½ BPF sebesar 149,6 Hz. Sedangkan kavitasi level 1 dapat dideteksi oleh spektrum envelope pada bentang frekwensi tinggi. Dapat disimpulkan pula bahwa penurunan ampitudo teramati secara umum pada domain waktu seiring dengan meningkatnya level kavitasi.

 

Abstract

Cavitation is an important indication of operation condition for a centrifugal pump. An indication of the appearance of cavitation is the formation of bubbles which collapse suddenly when the pressure changed on the suction side of the pump. The formation of cavitation bubbles can cause fault to the inner pump components. The fault that often results from cavitation phenomenon is affected in the impeller. This fault is usully identified through noise and vibration generated. Therefore, a method is needed to detect early cavitation phenomenon at the centrifugal pump. This study aims to develop cavitation detection methods using the vibration spectrum and envelope spectrum of low frequency band of 0-4 kHz and high frequency band of 4 kHz-8,5 kHz. In this study, cavitation detection in conducted by recording vibration signals that occur at centrifugal pump using an accelerometer. The data obtained is then transformed into the frequency domain and envelope spectrum using Fast Fourier Transform. The results were compared between normal condition and level 1, 2, and 3 cavitation. Comparisons were made on each vibration spectrum and envelope spectrum at the low frequency and high frequency bands. The result of this study showed that the vibration spectrum with low frequency band can detect the formation of level 3 cavitation with an increase in shaft frequency amplitude (47,26 Hz) and ½ BPF (149,6 Hz). Whereas early cavitation or level 1 cavitation was identified through the envelope spectrum at high frequency band. It also showed that a decrease in amplitude occured gradually in the time domain along with increasing level of cavitation.


Keywords


cavitation, centrifugal pump, vibration spectrum, envelope spectrum, frequency band

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References


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DOI: https://doi.org/10.18196/st.221231

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